Optical navigation sensors are commonly used in devices, such as an optical computer mouse, trackball or touch pad, for interfacing with personal computers and workstations. One technology used for optical navigation sensors relies on sensing light reflected from a surface using an array of photosensitive elements or detectors, such as photodiodes. Generally, outputs of the individual elements in the array are combined using signal processing circuitry to detect and track motion of a pattern or image in the reflected light and from that tracking to derive the motion of the surface relative to the array.
The optical navigation sensor described above will receive very weak signals when tracking on dark surfaces, and is subject to signal saturation when tracking on light surfaces. When this happens, the estimation of displacements become erratic and unreliable, hence affecting the overall performance of the optical navigation sensor.